Sur les interactions entre l'axe embryonnaire normal et les formations secondaires produites par la centrifugation de la blastula et de la gastrula chez les Amphibiens

Summary The complexes of organs induced by centrifugation of Amphibia blastulas or gastrulas interfere with the primary axis of the embryo: (a) explantates of centrifugated ectoblast are always poorer in differentiation than the same ectoblast leftin situ; (b) the complexes arising in the ventral part of the embryo have the tendency to elongate parallel to the main axis of the embryo and become connected with the head of the primary embryo; (c) grafts made on Axolotl eggs show that, when the reaction is poor, it cannot express itself except in cases of close contact with the normal organizer; (d) reciprocally, implants of strongly reacting centrifugated ectoblast placed on the ventral part of a normal gastrula of Pleurodeles induce modifications of the primary organs, viz. the transformation of the first somites into chorda.These facts lead to the conclusion that quantitative factors—and not qualitative—are effective in the differentiation of the embryo.     

Sur les substances cardiotoniques de la scille maritime(Scilla maritima L)

Sans résuméD'après une conférence donnée à l'occasion de la séance commune des sections de Nancy, Strasbourg et Mulhouse de la Société chimique de France et de la Société chimique de Bâle, le 14 novembre 1953 à Bâle.     

Réarrangements chromosomiques induits par les rayons X chez les Souris de race AKR/Tr

Summary A spontaneous translocated strain of mice (AKR/Tr.) with 36 acrocentric and 2 metacentric chromosomes received 400 R of whole-body X-irradiation. Cytological examination of dividing primary spermatocytes at the diakinesis-first metaphase stage of meiosis showed 6% of cells with chromosomal rearrangements.     

Sur le mécanisme de la régression du canal de Müller droit chez l'embryon de Poulet femelle

Summary In the in vitro experiments described above neither the hormone of the left ovary nor that secreted by the rudimentary right gonad brought about the regression of the right Müllerian duct of the female chick embryo. In castration experiments, this naturally occurring phenomenon had been found to depend either on the right gonad (Huijbers ⁴) or on both the right and left gonads (Wolff ^1–3).     

Sur les durées respectives du pouvoir attractif de l'épithélium germinatif et de la réactivité des cellules germinales à ce pouvoir,chez l'embryon de Poulet

Summary Experimental results of different authors show that the attractive stimulus of the germinal epithelium for the germ cells in the chick embryo lasts less long than the reactivity of these cells to the same stimulus. However, both of them (stimulus and reactivity) last far longer than the period of the incorporation of germ cells into the primordia of the gonads. Each of them disappears when an important phase of differentiation is about to start in the group of cells concerned.     

Sur les effets du 5-fluoruracile injecté à l'embryon de Poulet à des stades avancés de l'incubation

Summary 5-FU, injected into the chick embryo on the 5th and the 8th day of incubation, has an immediate lethal effect and a later lethal effect which are very attenuated. On the other hand, when injected in very high doses, the substance has a uniform teratogenic action and causes malformations which attain specifically the members, the brain, and the beak.

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Ces recherches ont été faites grâce à un subside du Fonds National Suisse de la recherche scientifique et de la Fondation E. Barell.     

Sur l'origine des mucopolysaccharides acides du néphron, étudiée in vitro

Summary The tissue culture of renal explants proves that the acid mucopolysaccharides, previously described in the distal convolution and the collecting tubule, do not result from urinary colloid precipitation, but from local epithelial secretion. Their physiological significance is discussed.     

Nouveaux résultats à propos de l'histologie nerveuse chez les Invertébrés

Summary Maillet's osmium-zinciodide technique gave interesting results in Arthropods by means of nerve histology. Tests demonstrated the importance of the chitinous cuticles as barrier to the particular staining properties of theMaillet's mixture. It would seem possible to compare this technique with theFalk's ⁸ fluorescence method.     

Sur des pigments rouges de Levures

Summary This preliminary communication describes red, watersoluble pigments elaborated by an adeninedeficient mutant of a haploid strain of yeast (Saccharomyces cerevisi). Acid hydrolysis of these pigments liberates a number of amino acids. Some of the physical and chemical properties of these yeast pigments resemble those of the antipernicious anæmia factor (vitamin B₁₂ ¹) which contains one atom of cobalt and three atoms of phosphorus, with a molecular weight of 1,500. Our yeast pigments contain no cobalt but one or two atoms of phosphorus, with an approximate molecular weight of 2,000.A report on the biological activities of our pigments will appear in the near future.     

Influence de la salinité sur la respiration tissulaire chez les Téléostéens

Summary Respiratory measurements by the Warburg method were performed on hepatic, renal and branchial tissues extracted from fishes (tench and eels), kept in either salt or fresh water. The oxygen consumption of hepatic tissues of both tench and eels increased when the fishes were transferred from fresh to salt water. No difference was observed for renal and branchial tissues.     

Sur les relations entre la production d'hexosamines et d'hydroxyproline de la part de fibroblastes cultivés in vitro dans différentes concentrations d'O2

Summary Studies and comparison of the hexosamine and hydroxyprolin production by fibroblasts cultivated in vitro at different oxygen concentrations. The results show that the highest hexosamine production occurs at a low oxygen concentration (5%). The highest hydroxyprolin production occurs at 20% O₂; this oxygen concentration is considered as an hyperoxic one for fibroblasts cultivated in vitro. Besides it has been ascertained that the highest sulphated MPS production occurs between 5 and 20% oxygen without any significant variation.     

Le rôle du nœud de Hensen dans la différenciation des somites chez les Oiseaux

Summary Our experiments prove that a piece of the Hensen's node may induce somite formation, even if it is transplanted at the head process stage into posterior parts of the primitive streak which cannot themselves form somites. Therefore, we conclude that the Hensen's node plays a very primordial role in somite genesis.     

Sur l'absence de biosynthèse des stérols et du squalène chez un coelentéré (anthozoaire), l'anémone de merCalliactis parasitica

Summary Sodium acetate I-¹⁴C has been injected to the sea anemoneCalliactis parasitica (coelenterate,anthozoa). Sterols and squalene were found unlabelled in this experiment. An analysis of the sterol mixture is reported.

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Nous remercionsMM. Cosson, Bardey etVarenne qui ont effectué les mesures de spectrométrie de masse sur un appareil AEI MS9, sous la direction du DrB. C. Das.

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Nous remercions le ProfesseurE. Lederer pour l'intérêt qu'il a porté à ce travail.

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Nous remercions la Station Biologique de Roscoff pour l'expédition de ces animaux.     

L'absorption intestinale de l'eau chez le lapin

Summary A rapid and efficient method of measuring the in vivo intestinal absorption of water is described. In male rabbits, absorption and transfer are very rapid, as shown by the presence of HTO in the protal serum immediately following its intraduodenal injection. A formula is given to express the relation between the average amount of water transferred and time.     

Sur l'absence de biosynthèse des stérols et du squalène chez un coelentéré (anthozoaire), l'anémone de merCalliactis parasitica

Summary Sodium acetate I-¹⁴C has been injected to the sea anemoneCalliactis parasitica (coelenterate,anthozoa). Sterols and squalene were found unlabelled in this experiment. An analysis of the sterol mixture is reported.

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Nous remercionsMM. Cosson, Bardey etVarenne qui ont effectué les mesures de spectrométrie de masse sur un appareil AEI MS9, sous la direction du DrB. C. Das.

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Nous remercions le ProfesseurE. Lederer pour l'intérêt qu'il a porté à ce travail.

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Nous remercions la Station Biologique de Roscoff pour l'expédition de ces animaux.     

Sur les intermédiaires de la désalkylation en C24 duβ-sitostérol par le criquetLocusta migratoria L.

Summary The locustLocusta migratoria L. transforms-sitosterol into cholesterol. Fucosterol, desmosterol and an unknown sterol (probably in C₂₉) are found to be intermediates, but not 24-methylene cholesterol.     

Effets comparatifs de JH-I et de JH-II chez Locusta migratoria L.

Summary Study of differential effects of JH-I and JH-II on metamorphosis, pigmentation and oocytes maturation shows evidence for a more specific action of JH-I in controlling metamorphosis.